Map making itself is something that you learn on the go. There may be some tutorials online (on some sort of wiki maybe if one exists).
I myself learned by just building map after map, starting with small dimensions. nowadays I know my way around with building some fine detailed maps.

Few tips: best way is to start with designing your map layout ('Terrain Modifications' under 'Tools') before going to place world objects ('Object Placement' also under 'Tools') after that finish up with territories.
Also (very important) after saving your map, fill in your map name under: 'Edit' > 'Mission Properties' > 'Mission Name'. If left empty your map shows as 'untitled' in map menu
Player objects btw are only used if one would build a scenario but that's something I don't work with.